Machine-switching telephone exchange system



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Oct. 20, 1925.

Oct. 20I 1925- v 1,557,596 w. E. LAMB ET AL MACHINE SWITCHING TELEPHONE 'EXCHANGE SYSTEM n Filed July a, 1921 2 sheets-Shen 2 Patented Oct. 20, 1925.

UNITED STATES PATENT. oFFlcE.

WILLIS E. LAMB, OF OAKLAND, AND RALPH' MASON,'0F IBERKIELEY,` CALIFORNIA,

ASSIG-NORS TO AMERICAN TELEPHONE AND TELEGR-APH COMPANY, A CORPORA- TION OF NEW YORK.

MACHINE'-SITCXE'IING'` TELEPHONE EXCHANGE SYSTEM. 4

Applioatonled July 8,

17 'o all whom t may concern:

Be it known that we, WILLIS E. LAMB and RALrH IV. MASON, residing at Oakland and Berkeley, in the county oi' Alameda and State of California, have invented certain Improvements in Machine-Switching Telephone Exchange Systems, of whichthe folf lowing `is a specification.

`This invention relates to machine switching telephone exchange systems.

Its object is to provide an improved system employing what are known as two hundred point switches.

In the system of this invention the selectors and connectors have two sets of talking brushes and two test wipers. The selector is iirst raised a number` of steps corresponding to the rst digit and then automatically rotates, testing two trunks at each step, moving on it both are busy and it one is idle, seizing it. The calling-line is thus extended to a succeeding` linkcircuit which may be a connector. `The set ot brushes of this connector rendered opera-` tive is determined by the odd or` even character of the digit involved insetting the preceding selector. Inasmuch as a given connector takes care of two hundred lines it is reached over either one oitwo levels of the preceding selector. In order to render the brush set serving the desired hundred of the two hundred lines terminating in the connector operative, one of the talking wires from say the even hundreds level in the preceding selector from which the connector may be reached,` includes a switching magnet which operates only when the digit involved in setting the said selector is even and connects the brushes servingl the even hundred group to the calling end of the circuit. This magnet in operating locks itself by a circuit through a second winding and short circuits the winding inthe talking conductor to remove it from the conversational circuit. The conductor from the oddy hundreds level of the selector from which the same connector is reached does not include this switching magnet, and `conse- 1921. Serial N'o. 483,305.`

quently the other set of brushes is left connected to the calling end of thecircuitwhen the connector is seized from this level.

Referring to the drawing, Figure 1 shows the calling line and a. selector, and Fig. 2 shows a Vconnector anda pair of substations.Referring to Fig. 1, the removal of the receiver at substation Aca-uses a. line switch, not shown, to seize a first selector shown in Fig. 1. The impulse relay IR of this selector is now energized over the following circuit: free pole of battery, leftI winding of relay IR, Fig. 1, armature 100 and back contact of relay D1, lower talking d conductor, through the loop at the substation A, upper talking conductor, `armature .101 and back contact of relay D1, conductor 102, right non-inductive winding of relay IR, switch 103 operatedon the eleventh Irotary step of the selector, secondary winding o1- the induction coil 104to ground. This induction coil is provided for the purpose of. giving a dial toneto theV subscriber to intorni him when the circuit is ready to ref;

ceive impulses.'A `When the relayIR operated.,` it energized the` usual first slow relay T1 over the :following` circuit: free vpole of battery, relay T1, `armature,and front contact of relay IR, conductor 106, to'ground at the` armatureV 107 andback contact of the relay D1. n Slow ,relayv Tl holds up over the-line circuit interruptions and prepares a circuit `for relay El. Now uponthe first retraction of the impulse `relay IR as the iinger wheel after being rotated by the party at substation A restores to normal, the relay El operates from ground on the armature 107` of relay D?, landilocks itself over the following circuit: `free pole of battery, relay El, its rightarniature and frontwcontact,

vconductor `108, armature andiback contact ductors 111, 109, 110 to ground at the left armature and front contact of relay T1. The vertical magnet 105 at the end of its stroke opens the locking circuit of the. relay E1 which releases. In releasing its left armature, this relay opens the circuit of the magnet 105 which releases. This occurs before the backcontact 112 of the impulse relay IR is again closed, as the finger wheel interrupts the line ciicuit the second time. lVhen this interruption occurs and the contact 112 is again closed, the same operations take place, the relay E1 initially energizing from ground at the armature 107, locking itselfto ground at its right armature and front contact, transmitting an impulse to the vertical magnet 105 and slow relay C1 in series, the vertical vmagnet at the end of its stroke opening the lockingl circuit of the yrelay E1, which in releasing again releases the vertical magnet,` whereupon the circuit is ready for the next iinpulse. The relay C1 being slow remains lenergized during the transmission of the vertical impulses.

When this relay energized at the beginning of the impulses it operated relay F1 'over the following circuits: free pole 'of battery, relay F1, armature and back contact of the rotary magnet 114, off-normal switch 115, conductor 116, armature and front contact of relay C1 to ground. Relay F1 in attracting its upper armature locked itself to ground over conductor 110 and the leftarinature and front contact of slow relay T1 which holds 'up after the impulses' are transmitted. In 'attract-ing itsa'ri'nature 117, relay F1 operates the brush shitting relay B1. In attracting its'` armature 118', relay F1 prepares the circuit of the rotary magnet 114. A short interval after the relay E1 releases when the vertical magnet interrupts its circuit on the;

receipt'ot' the last vertical impulse, the relay C1 releases, closing the circuit 'of the rotary magnet 114 which thereupon steps the selecfer iii-ashes 150,151,128, 142, 143, 136,*01110 the iirst pairol trunks in the selected level. A level is made up `of -two horizontal rows of ten trunks each. If both ofthese firstv trunks are busy, the switch Twill move on to testthe next two trunks. These trunk groups it will be understood are equivalent. If one of the trunks is idle, the switch will stop and seize such trunk. l, Assuming that 'both trunks, first tested, are busy, both test' multiples 202, 201, are then grounded. It will be remembered that relay B1 operated when relay F1 operated at the beginning of the vertical movement of the selector. until the' end of the stroke of the rotary magnet 1.14 and consequently relay B1 will hold up over its arma-ture 125 and front Contact, contact 126 of relay D1, conductor 127, test brush 128 to ground on the test Relay F1 does not release;

multiple 202 before its original energizing circuit is opened by the retraction of armature 117 of the relay F1. Ground being also present on the test multiple 201 of the other trunk, an impulse is transmitted to again operate relay F1 for transmitting another impulse to the rotary magnet to advance the brushes a step onto the next two trunks. The circuit for relay F1 is 'as follows: free pole of battery, relay F1, armature and back contact of magnet 114, oit-,normal switch 115, conductors 116,129,130, arii'iatifiie`y 131 and back contact of relay D1, conductor 132, armature and back contact of selector release magnet 133, conductor 134, armature 135 and front Contact of relay B1, test brush 136 to the grounded test terminal 201. The circuit for the' rotary magnet ,114 includes the armature 118 of the relay F1 and normal contact of the slow relay C1.l n

Assuming now, that when the brushes engage the next two trunks, the trunk shown in full in Fig. 2 is idle. AIn that event, ground is present on the test multiple 202 ofL the other trunk and the test multiple 201 is open. The presence of ground on the test multiple 202 of the other trunk causes the switching relay B1 to remain operated as before, and due to the absence of ground on the test multiple 201, the relay F1 is not again energized to step the selector ahead. The absence of ground on test multiple 201 also permits the switching relay D1 to operate `over the following circuit: free pole of battery, relayF1, armature and back contact of the rotary magnet. 114, (id-normal switch conductors 116, 129,137, switch 138, operated on the eleventh 'rotaryzstepI ielay'D1,coiiductor `139, 141, 110 to ground at` the left armature and front contact of the slow relay T1. Relay F1 is marginal Vand does not operate'in this circuit. Relay D1 did not operatewhen-the iirst two trunks were tested and found busy due to the shunt about its winding closed over the conductor 130, armature 131 and back-contact of said relay, conductor 132, armature and backcontact ot"v the release magnet- 133, conductor 134, armature 135 and its front contact brush 136 tothe ground on multiple 201. The swit hingrelay D1 in attracting its armature I140 closes asubstitute holding circuit for the relay B1as follows: free pole of battery; relay B1, armature 125 and front contact `\of said relay, armature 140, and front e'o'ntactfof relay D1, conductors 139, 141, togrouiid 'at the left armature andl front conta'ct of relayT1. Relay D1 in attracting its arniatures 101 `and 100 extends the talking conductors through tothe impulse relay 219-of the connector which now operates over'th'e calling line circuit. Relay 219 in attracting its armature energizes the usual 'first slow relay 221 of the connector which vin attracting yits upper "armature grounds the release wire 200 leading back to the preceding selectors. It will be understood that a number of selectors like that of Fig. 1 are interposed between the firstselector and connector before the slow relay of the preceding selector corresponding to slow relay T1 releases due to its circuit being opened by the release of its impulse relay when the switching relay "corresponding to Dl disconnects it from the calling line. Therefore, the relays similarto D1 are held up over parallel circuit similar tothe following circuit: free pole of battery, relay F1, larmatmre and back contact of magnet 114, olf-normal switch 115, conductors 116, 129,` switch 138, relay D1, conductors 139, 147, armature 131 and front contact of relay D1, conductor 132, armature and back contact of the release magnet 133, conductor 134, armature 135 and front contact of relay B1, brush 136, multiple 201 to the grounded sleeve wire 200. This ground also causes the seized trunk shown in Fig. 2 to test busy in both levels in which it appears. t

Assuming, on the other hand, that the trunk 202, 203 was idle and the trunk shown in full in Fig. 2 was busy, the test multiple 202 would be ungrounded, and the test multiple 201 would be ground-ed. Due to the absence of ground on test. multiple 202, relay B1 would release when its eircuit is opened by the retraction of the armature 117 of relay F1 and shiftv the trunk talking conductors 14S and149 to the upper talking brushes 150, 151. Although ground is presenten the test multiple 201 when the brush 136 encounters such terminal, relay B1 releases before this ground is applied long enough to operate the relay ll" and allow the rotary magnet to magnetize sufficiently to give the selector another step. As soonv as the armatures 145 and 152 release, the impulse relay corre sponding to 219 of said trunk operates over the calling lineienergizing slow release corresponding to 221, which supplies ground to the sleeve wire 200 leading back to the test multiple thus providing a substitute circuit for the relay D1 before the ycircuit of such relay is opened by the release of the slow relay as before. This ground, also causes the .seizedV trunk to test busy in both levels in which it appears.

Referring to Fig. 2, it will now be necessary to explain how the selection of ay given linel in a 200 point connector is secured, the finger wheel operating on` the decimal basis. The second and third selectors (net shown) but which would be similar to the rst selector shown in Fig.` 1 are set to the. desired levels and have seized trunks. lThe multiples 205, 206, 201 of the connector appear in an even level and the multiples 29T, 206, 209 appear in an odd level of the third selector. brush shifting `transmission of the impulses.

magnet 249 is 'included in circuit with the impulse relay 219 when the connector is seized from the even `level and shifts the trunkconductors 210, 211, 212 into connection with the brushes 213, 214, 215 serving the even hundred lines of the connector. This magnet is not operated when the connector is seized from the odd levelV and allows the trunk conductors to remain in con-l tact with the brushes 216, 217, 213 serving the odd hundred lines in the connector.

Assuming that the hundreds digit even the following circuit is closed for the impulse relay 219 and relay 249; free pole of battery,upper winding of relay 219, normal contact ofrelay 220, conductor 271, lower winding of relay 249, conductor 204, multiple 205, brush 142, armature 145 of relay B1, conductor 14S, armature 101 of relay D1, through the substation loop, armature 100 of relay D1, conductor 149, armature 152 of relay B1, brush 143, multiple 206, conductor 270, normal'contact of relay 220, lower windingof relay 219to ground. relay 219 operates slow relay 221, preparing the circuit of the vertical magnet 222. Relay l221 in attracting its upper armature grounds multiples 201 and 209 to render this connector busy in both levels in which it appears'. The calling party now transmitsthe tens impulses. .Each time the relayf219 closes its back contact an impulse is transmitted to the vertical magnet 222 over a circuit, including contact 223 of off normal switch 224 and the slow relay 225, which holds itself ,operated duringl the Contact 223 opensron tlie'first step ofthe switch and contact 226 closes so that the impulses after the first, pass by way ofthe armature and front contactof relay225. When the impulses cease, slow relay225 releases and connects the rotary magnet to the back contact of Fthe impulse relay and upon the transmission of the units impulses the rotary magnet 22? steps the brushes around auuimber lof steps corresponding to `the number of the'nnits impulses. Slow relay 231 holdsup during these impulses and rcleases when they cease. 1t having been assumed that the hundredths digit was even the rela-y 249 which operated-when the connector was seized. loclieditself over its up* per winding` to ground under control of the release magnet 234. Therefore the brushes 213, 214 and 215 serving the even hundreds", are `in circuit with the trunk conductors 210, 211, 212, and an even hundreds line, which we will assuineto be the one. designated'l, has been selected. "1 test of the line now takes place@u lf the line is' busy ground is present on its multiple 229 whichoperates 'relai' 2.3) over the following circuit free pole of battery, relay 230, uppermost armature and back contact of relay 232, upper armature and front contact of slow relay 231, conductors 237, 210,V brush 215 to ground on the test multiple 229. Upon the release of slow relay 231, relay 230 locks itself to ground on conductor 200. Relay 230 in attracting its upper armature prevents relay 232 from operating and applying ringing current to the line, and in attracting its lower-most` armature applies busy tone from source 233 to the calling line. wWhen the calling party replaces his receiver relay 219 releases, r-eleasing relay 221, the inert condition of these relays operating the connector release magnet The retraction of armature 235 of relay 221 removes ground from release wire 200, deenergizing relay D1 of the first selector, and similar relays of theot-her selectors in the switch train and also releases the. line switch. The retraction of armature 107 of relay D1 closes the circuit cf release magnet 133 of the first selector.

Assuming however that the called line is idle, full potential is present on multiple 229 and relay operates over the-following circuit: free poleof battery, relay 236, multiple 229, brush 215, conductors 210, 237, upper armature and back contact of relay 231, lower winding of relay 232, upper armature and back Contact of relay 230 to grounded release wire 200. Relay 232 in attracting its upper armature locks itself to conductor 23S, grounded at the lowermost armature of relay in attracting its armature 239 relay 232 grounds the test multiple 229 to render 'the selected line busy. In attracting its armatures A0', 2-11, relay 232 connects ringing current to the called line from source 2-l-2, this circuit'including the upper' winding of the ringing cutoff relay 243. 'Vhen the called party answers, this relay operates removing the ringing current and in attractin its ai mature 211%, locks itself to grounded conductor 238. In attracting its armatures 2&5 and :2v-itl, relay 243completes the conversational circuit. Relay 220 energizes in series with the called vline and' reverses the direction et' current l'iow inithe callingv line for metering lmrposes in the well-known manner. l.

Upon the replacement ofthe receiver by the calling partyafter the termination of the conversation the connection is released as described in the case of a `busy line.

lf the connector had been seized from the cddlevel at multiples 207, 208, 209; that is to say if the hund-reds digit was odd, the relay 249 would not have been operated and the brushes 216, 217, r21S would remain in connection with the `trunk conductors 210, 211, 212 and at the end of the rotary -movement of the connector these brushes would extend the calling line to substation C, thel corresponding line in the odd hundreds.

The other operations wouldbe the same those described in detail.

lhile only one selector is shown it will be yunderstood that in actual practice a second and third selector would also be used, the connector shown being accessible from levels in the third selectors.

lVhat is claimed it:

1. In a telephone system, a connector switch having a pair of bush sets, groups of called lines to which said switclrhas access, terminal banks leading to said connector, a brush shifting relay in said connector for rendering operative the proper connector brush set, a circuit including said brush shifting relay closed over the' talking conductors of said connector switch via certain of said terminal banks for operating said brush shifting relay, arelease magnet in said connector switch, and a locking circuit for said brush shifting relay including a contact of'said release magnet. f I

In a telephone system, Aa calling line, a connector switch having a pair of brush sets, groups of called lines towhich said switch has access, terminal banks leading` to said connector, a brush shifting relay in said connector for rendering operative the proper connector brush set, a circuit including a winding of said brush shiftingl relay closed lover the vtalking conductors of said connector' switch via certain of said terminal banks for operatingvsaid brush shifting relay, a slow relay, means responsive to the extension of said callinglr line to said connector for operating said slow relay to remove tho winding of said brush shifting relayy from the talking circuit, a release magnet in said connector, and a locking circuit for said brush shifting relayl including a Contact of said release magnet.

3. -ln'a telephone system, a switch, ar pl urality of sets of correspondingly positioned brushes on said switch,` a series of sets of contacts for each of said. sets of brushes, a connecting circuit extending to said switch, .multiple terminal contacts for said connecting circuit, a relay to theback'contacts of which one of said brush sets is connected, the other brush set being connected to the front contacts of said relay, a circuit for said,vr relay automatically completed lwhen connection is made to certainbfsaid muln tiple terminalsets, a release magnet in said switch, and a locking circuit for sai-d relay including anwarmature thereofand a contactof said release magnet.

Ll. :In a telephone system, a switch, a plurality of sets of correspondingly positioned brushes on said switch, a `series of sets of contacts for each of saidsets of brushes, a connecting circuit extending to said switch, multiple terminal contacts for said connecting circuit, a relay arranged to render one of said brush sets operative when said relay ture thereof and a normal contact of said is deenergzed, the other brush set being release magnet. 10 rendered Operative When Said relay iS enel- In testimony whereof7 We have signed our gized, a circuit for said relay automatically names to this specification this 28th day of completed when connection is made to cer- June 1921.

tain of said multiple terminal contacts, a

release magnet in said switch, and a locking WILLIS E. LAMB. circuit for said relay including an arma- RALPH MASON 

